If you save Narre and choose not to kill him, you will not be able to find him again for the rest of the game.
In this case, the mushroom leader may be dissatisfied with your behavior, but it will not affect the progress of the game.
Rescue Nare and protect the slaves - the branch "Rescuing Ulbrun" continues, fighting the gray dwarves and Nare.
Rescued Nare and did not protect the slaves - "Rescuing Ulbrun" failed and fought with the gray dwarves.
Rescued Nare, only protecting the gray dwarves - "delivering Nare's head" failed, and fought with Nare.
Regardless of Nare, take a long rest in the camp - the gray dwarves and slaves disappear, you can complete "Delivery Nare's Head", and you can also pick up his items.